Automatic chemical mixer

ABSTRACT

A demand responsive system for automatically mixing and replenishing liquid chemicals subject to degradation when mixed, including collapsible storage vessels for the unmixed chemicals, a small reservoir for storing and mixing chemicals, pump means to transfer chemicals from the separate storage vessels to the reservoir at rates higher than the demand rates, valve means within the reservoir for maintaining the reservoir level within selected limits, and means for connecting the reservoir with a chemical user. For photographic film processors, for example, the system functions on demand to periodically replenish a mixture of A and B type working solutions, while also supplying fixer and water if desired. This system supplies adequate amounts of the mixture on demand with a minimum of deterioration by premixing only an amount which may be needed for immediate use. The system is completely automatic and needs no operator control.

United States Patent Ray [151 3,705,598 5] Dec. 12,1972

[54] AUTOMATIC CHEMICAL MIXER [72] Inventor: Manuel C. Ray, Palos Verdes Peninsula, Calif.

[73] Assignee: National Research and Chemical Company [22] Filed: Dec. 4, 1970 [2]] Appl. No.: 95,108

[52] U.S.Cl. ..l37/l0 l.25,l37/567,4l7/4 [51 Int. Cl ..Fl6k 19/00 [58] Field of Search....137/l0l.25, 101.27, 114, 567;

[5 6] References Cited UNITED STATES PATENTS I 3,345,997 10/1967 Milleret al. .....l37/l0l.25 X

Primary Examiner-Robert G. Nilson Attorney-Fraser and Bogucki cuamims ruin itimis FOR CUBITAINERS so Q | roman cum FOR sotunoi $r 1v; COIIFOIEITS RESERVOIR 5 mi 10 r oqsssoi WATER 1o \l [57] ABSTRACT A demand responsive system for automatically mixing and replenishing liquid chemicals subject to degradation when mixed, including collapsible storage vessels for the unmixed chemicals, a small reservoir for storing and mixing chemicals, pump means to transfer chemicals from the separate storage vessels to the reservoir at rates higher than the demand rates, valve means within the reservoir for maintaining the reservoir level within selected limits, and means for connecting the reservoir with a chemical user. For photographic film processors, for example, the system functions on demand to periodically replenish a mixture of A and B type working solutions, .while also supplying fixer and water if desired. This system supplies adequate amounts of the mixture on demand with a minimum of deterioration by premixing only an amount which may be neededfor immediate use. The system is completely automatic and needs no operator control.

7 Claims, 3 Drawing Figures PROCESSOR E- o PRMESSOR PATENTED um: 12 1922 .SHEET 1 OF 3 OUBITAINERS ENPTY ALARNS FOR CUBITMN S PORTION OHEON FOR SOLUTION COMPONENTS INVENTOR.

MANUEL C. RAY

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AT'T ORNEYS PATENTEDHEB 2 I972 3. 705 598 sum 2 0r 3 CONTROL CIRCUITS msuam VESSEL FIG.- 2

INVENTOR. B2 DRAIN MARUEEL C. RAY

ATTORNEYS T0 PROCESSOR AUTOMATIC CHEMICAL MIXER BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to systems for the storage and replenishment of mixtures on demand and more particularly to systems for supplying chemicals on demand to photographic film processors.

In processing photographic film in an intermittently or continuously operable processor system, chemicals known as Type A replenisher and TypeB replenisher are consumed at varying rates dependent upon machine usage, film size and the character of the exposed images. In addition, a third chemicalknown as a working solution must be periodically replenished. The working solution is added separately, but the Type A and Type B replenishers must be premixed in proper proportions before they are added to the film processor. Once the Type A and Type B replenisher solutions are mixed together they begin to deteriorate because of oxidation. This deterioration not only increases cost because of wasted chemicals, but also makes difficult determination of how much deteriorated mixture must be added. However, if the replenisher solutions are mixed in smaller quantities they must be mixed more frequently and labor costs are increased. Many different film processors are in use, and while they have their own pumping systems for withdrawing chemicals from a supply, modification of such existing units is not feasible.

2. Prior Art Replenisher chemicals for film processor units are presently hand mixed in large open tanks, resulting in relatively high costs for both chemicals and labor. Chemical costs are high because the A and B replenisher solutions oxidize while stored in the large containers prior to use. Furthermore, the hand mixing can result in spilling and mixing errors. Because of these errors and because the amount of oxidation is unknown, it is impossible to know the exact proportions of chemicals in the containers. Labor costs are unnecessarily high because of the time required for hand mixing and for periodically cleaning dirt and oxidized chemicals from the tanks. In addition, because the chemicals are mixed in large quantities, the proportions and strengths of the chemicals cannot be easily varied to meet changing demands.

SUMMARY OF THE INVENTION Means are provided to insure uniformity of flow and mixing, permit ready monitoring of flow rates and to indicate when a storage container is empty.

In a specific example of a system in accordance with the invention, a cabinet which encloses the mixing pump provides storage and ready accessibility on an upper shelf for containers of concentrated chemicals,

feed lines from which pass into the interior of the cabinet. Water is supplied at conventional pressure by a standard utility water line. Type A and Type B replenisher chemicals are fed by separate pumps in desired proportions from the storage containers through separate level sensing vessels and control valves to a small reservoir having a capacity of about 2 quarts, where they are mixed with each other and with water from the water line. Freshly mixed replenishment solution from the reservoir and working solution from a container stored on the shelf are thus available on demand of the photographic processor. A level sensing device within the reservoir automaticallycontrols the mixing pumpv to maintain the level of the replenishment solution between selected limits within the reservoir. When the level is at the low limit, control circuits responsive to the level sensor start the pumps first, then open the valves after a predetermined delay. The water pressure is concurrently reduced at a pressure regulator, so that the flow rates and proportions of the constituents are held constant throughout.

The system advantageously utilizes source chemicals stored in cardboard boxes with collapsible plastic interior liners. The cardboard boxes give the containers rigidity as well as a convenient size and shape for ease of handling while the plastic liner provides a non-leak seal and avoids the introduction of air into the system. The containers are readily accessible for inspection and replacement, but neatly stored in readily manageable form requiring no tank cleaning.

Control systems and features in accordance with the invention provide an alarm when one of the storage containers has been fully drained but before the system has run dry. The level sensing vessels in the flow conduits include level sensors to signal that a container is empty, and the control system also inhibits operation of the entire system to prevent the supply of an improper mixture to a chemical user. The control system also operates a mixer within the small storage reservoir during the pumping of chemicals and for a predetermined time thereafter.

The system further incorporates a test feature with appropriate valves for measuring flows from the system. The operator may actuate a control town the pump for a predetermined time, causing the source chemicals to be diverted to a measuring vessel. I

BRIEF DESCRIPTION OF THE DRAWINGS A better understanding of the invention may be had from a consideration of the following detailed description, taken in conjunction with the accompanying drawings, to which:

FIG. 1 is a partially broken away perspective view of a demand responsive automatic mixer system according to the invention;

FIG. 2 is a detailed perspective view, partially broken away, of a portion of the mixer system of FIG. 1; and

FIG. 3 is a schematic and block diagram of a control system used in conjunction with the system of FIG. 1.

DETAILED DESCRIPTION Photographic film processors typically move film through two processing steps and a wash step in the course of processing. The first step contains a mixture of two chemicals known as Type A and Type B replenishers which are consumed during the development process and must be periodically replenished. The second step utilizes a premixed fixer solution which must also be replenished from time to time. These processors also have need for water which is utilized during a wash step and which is used to dilute concentrated source chemicals. The processors include pumps to withdraw chemicals at a demand rate, typically from a large static container.

. As shown in FIG. 1, an automatic mixer system includes a cabinet 12 having an upper shelf 14 supporting collapsible plastic liquid containers 16, l7and 18 containing source chemicals. The shelf 14 provides convenient storage as well as ready accessibility. Containers of this type within durable, rigid, cardboard shells are commercially available under the trademark CUBITAINER.

As also shown in somewhat more detail in FIG, 2 with respect to the container 16, liquid chemicals flow from the containers 16, l7, 18 through conduits 20, 21, 22 to level sensing vessels 24, 25, 26 respectively. Each level sensing vessel contains a float valve assembly 28 (FIG. 2 only) actuating a sensor switch 29 to provide an empty signal when chemical flow from the associated chemical container ceases. The empty signal is initiated before the system runs dry and inhibits further operation of the system, thereby preventing the mixture of chemicals in improper proportions. A warning signal may also be communicated to the operator of the associated film processor as by a panel light or audible alarm (not shown).

From the level sensing vessels 24, 25, 26 the chemicals flow through conduits 30, 31, 32 to pumps 34, 35, 36 respectively. Fixer solution from container 18 is pumped independent of the other chemicals by pump 36 directly to the associated film processor (not shown) through a conduit 39 in response to commands from that unit. From pumps 34, 35 Type A and Type B chemicals pass through conduits 40, 41 to solenoid actuated valves 42, 43 respectively. The valves 42, 43 are electromechanically controlled in a conventional manner as by a solenoid or other device to block or permit flow therethrough and insure the mixture of Type A and Type B chemicals in a selected proportion.

From the valve 42 Type A chemical flows through alternate conduits 46, 47 to a mode control valve 48, while Type B chemicals flow from the valve 43 through alternate conduits 50, 51 to a mode control valve 52. The mode control valves 48, 52, which are shown as manually controlled but may be operated by solenoids in more expensive systems, have a function analogous to a single-pole double-throw switch, passing chemicals either from conduits 46, 50 through conduits54, 55 respectively to a small reservoir 58 when in an operate mode, or passing chemicals from conduits 47, 51 through conduits 60, 61 respectively to measuring vessels (.not shown) when in a test mode.

A pressure control valve 64 in this instance is connected to a standard utility water supply (not shown) and supplies water under selected, controlled pressure through conduit 65 to the associated film processor as needed on a continuous or separately controlled basis and through conduit 66 to an adjustable flow rate solenoid operated valve 67 similar to the valves 42 and 43 which control the flow of Type A and Type B chemicals. From the valve 67 water passes through a mode control valve 68, passing alternatively through conduits 70 and 71 to a measuring vessel or device (not shown) or through conduits 72 and 73 to the reservoir 58. The mode control valve 68 operates in a manner similar to the mode control valves 48 and 52.

The reservoir 58 has a capacity of approximately two quarts. While the size of the reservoir is not critical, it should be large enough to supply chemicals to the associated chemical user during the time delay required to begin refilling of the reservoir while maintaining the quantity of chemicals which is mixed and subject to deterioration at a minimum. The reservoir 58, seen in detail in FIG. 2, includes a mixer 76 rotated by a motor 77 and a level sensor float 78 operating a switch 79. A conduit 82 carries chemicals from the reservoir 58 to the associated cl migal processing system, which includes its own pumping means to demand a chemical supply by withdrawing fluid.

The operation and control of the chemical mixer system is best described in conjunction with the overall control system of FIG. 3 wherein components are represented by hollow rectangles having numerical designations consistent with FIGS. 1 and 2. FIG. 3 illustrates in detail the relationships of the various elements of the control system which are shown more generally in FIGS. 1 and 2. When the chemicals within the reservoir 58 drop below a selected level, as when chemicals are drawn off by the associated film processor (not shown), the level sensor 78 controls a switch 79 to provide a fill signal to inhibit circuits 84. When the reservoir becomes full this condition is detected by the level sensor float 78 causing the switch 79 to terminate the fill signal.

Each of the level sensing vessels 24, 25 and 26 include a float valve assembly represented schematically as a level sensor float 28 controlling a switch 29. When fluid within the level sensing vessels 24, 25, 26 drops below a selected point, as when the associated chemical container becomes empty, the level sensor float 28 controls the switch 29 to provide a signal to an alarm indicator 86. When the alarm indicator 86 receives the signal it responds by providing a visual or audible alarm to an operator of the associated photographic film processor and also provides a signal to the inhibit circuits 84. The inhibit circuits 84 respond to the signal from the alarm indicator 86 by inhibiting the fill signal. In this manner, the chemical mixer automatically prevents chemicals from being pumped to the reservoir 58 and mixed in improper proportions when one of the containers 16, 17, 18 becomes empty.

When not inhibited the fill signal passes from inhibit circuits 84 to pumps 34 and 35 and through shut-off delay 88 to the mixer 76. The pumps 34, 35 begin pumping immediately upon receipt of the fill signal and cease pumping immediately upon cessation of the fill signal. The mixer 76 begins operation immediately upon receipt of the fill signal but the shut-off delay 88 causes the mixer to continue operating for several seconds after discontinuation of the fill signal. This continued operation of the mixer insures the complete mixing of the chemicals which enter the reservoir 58 immediately prior to discontinuation of the fill signal. The fill signal also passes through delay 90 to three solenoids 92 which control the valves 42, 43 and 67 causing them to open in response to the fill signal and close upon discontinuance of the fill signal. The delay 90 causes the solenoids to open the associated valves approximately 8 seconds after initiation of the fill signal by the switch 79 but closes the valve immediately upon discontinuance of the fill signal. This short time delay before opening the valves 42, 43 and 67 insures that the pumps 34 and 35 have built up a constant, uniform pressure before the valves are opened. This arrangement assures fluid flow at the selected rate and mixing in the proper proportions.

An automatic mixer system 10 in accordance with the invention also includes a test mode enabling the operator of an associated film processor (not shown) to easily ascertain the proportions in which the Type A chemical, Type B chemical and water are being mixed. To operate the system in the test mode, the operator manually turns the mode control valves 48, 52 and 68 to atest position and depresses a pushbutton test switch 94. The depression of the pushbutton test switch 94 produces a test refill signal which is transmitted to the inhibit circuits 84 and causes the system to react in the same manner as when a refill signal is produced by the switch 79 associated with the reservoir 58. However, because the mode control valves have been switched from an operate mode to a test mode position, the fluid flowing through the valves 42, 43 and 67 is diverted to separate measuring vessels rather than the reservoir 58. When the operator feels he has an adequate sample, he merely releases the pushbutton test switch 94 discontinuing the test refill signal and causing the system to cease operation in the same manner as when a refill signal is discontinued by the switch 79. Because the system operates exactly the same when in the test mode as when in the operate mode, the measuring vessels contain chemicals in exactly the same proportions as are mixed in the reservoir 58 when the system operates in the operate mode. Thus, the operator can easily determine if adjustment of the valves 42, 43 and 67 is needed to attain a mixture of the correct proportions in the reservoir 58. Although the mode control valves 48, 52 and 68 and the pushbutton test switch 94 have been shown as manually operated in the preferred embodiment, in a more expensive arrangement the mode control valves might be operated by a solenoid responsive to the test fill signal and the pushbutton test switch 94 might be replaced by an automatic timing device.

Although there has been described above a specific arrangement for a chemical mixer system in accordance with the invention, for the purpose of illustrating the manner in which the invention may be used to advantage, it will be appreciated that the invention is not limited thereto. Accordingly, any and all modifications, variations or equivalent arrangements which may occur to those skilled in the art should be considered to be within the scope of the invention.

What is claimed is: 1. An automatic liquid chemical mixer for use with a photographic film processor comprising:

at least two chemical containers each storing a different chemical; a reservoir having a small capacity in relation to said containers; pumping means responsive to the level in said reservoir for transferring chemicals from said con tainers to the reservoir in selected proportions to maintain the quantity of fluid within the reservoir between specified limits; and

means for diverting chemicals from said pumping means to containers external to said reservoir upon command.

2. An automatic liquid chemical mixer comprising:

at least two chemical containers each storing a different chemical;

a reservoir having a small capacity in relation to said containers; and

pumping means responsive to the level in said reservoir for transferring chemicals from at least two of said containers to the reservoir in selected proportions to maintain the quantity of fluid within the reservoir between specified limits, said pumping means including valve means opening to allow the passage of chemicals at a selected rate for a selected period of time only after said pump means has been activated for a short period of time to create a selected pressure.

3. An automatic liquid chemical mixer for use with a photographic film processor comprising:

at least two chemical containers, each storing a dif ferent chemical, each of said containers including an outer structure defining a rigid volumetric container and a collapsible inner structure providing a liquid-tight seal;

a reservoir having a small capacity in relation to said containers; and

pumping means responsive to the level in said reservoir for transferring chemicals from said containers to the reservoir in selected proportions to maintain the quantity of fluid within the reservoir between specified limits.

4. An automatic liquid chemical mixer for use with a photographic film processor comprising:

at least two chemical containers, each storing a different chemical;

a reservoir having a small capacity in relation to said containers;

pumping means responsive to the level in said reservoir for transferring chemicals from said containers to the reservoir in selected proportions to maintain the quantity of fluid within the reservoir between specified limits; and

means for detecting an empty condition in one of said containers and providing a signal in response to such an empty condition, said signal activating a means for warning a machine operator and means for inhibiting said pumping means.

5. An automatic liquid chemical mixer for use with a photographic film processor comprising:

a storage container for Type A chemical solution;

a storage container for Type B chemical solution;

a storage container for working solution;

means connecting the chemical mixer to a water pp y;

a reservoir having a small capacity in relation to said containers for Type A and Type B chemical solution;

pumping means responsive to the level in said reservoir for transferring chemicals from said containers for Type A and Type B chemical solution to the reservoir in selected proportions to maintain the quantity of liquid within the reservoir between B chemicals respectively; specified limits; a pair of pumps, each coupled to a different conmeans for transferring fluid from the reservoir to the tainer, and each having a rate proportionately film processor upon demand; higher than a given demand rate; means for transferring fluid from said storage cona closed reservoir coupled to the pair of pumps and tainer for working solution to the film processor in l g means p g to the demand y upon d m nd; nd said reservoir having a substantially smaller means for providing water to the film processor upon p y than Said Containers; and

demand. liquid level sensing means coupled to said reservoir 6. For use with an automatic film processor, a chemil0 and Controlling said P of P p cal Supply device comprising; 7. The chemical supply device of claim 6 further ina chemical Supply System providing a Type A and cluding solenoid valve means connected between the Type B chemical mixer f given demand rates pumps and the reservoir and time delay means responf a demand System, demand being indepen sive to the level sensing means controlling the valve dently intermittent or continuous, comprising: means- I a pair of collapsible containers for Type A and Type 

1. An automatic liquid chemical mixer for use with a photographic film processor comprising: at least two chemical containers each storing a different chemical; a reservoir having a small capacity in relation to said containers; pumping means responsive to the level in said reservoir for transferring chemicals from said containers to the reservoir in selected proportions to maintain the quantity of fluid within the reservoir between specified limits; and means for diverting chemicals from said pumping means to containers external to said reservoir upon command.
 2. An automatic liquid chemical mixer comprising: at least two chemical containers, each storing a different chemical; a reservoir having a small capacity in relation to said containers; and pumping means responsive to the level in said reservoir for transferring chemicals from at least two of said containers to the reservoir in selected proportions to maintain the quantity of fluid within the reservoir between specified limits, said pumping means including valve means opening to allow the passage of chemicals at a selected rate for a selected period of time only after said pump means has been activated for a short period of time to create a selected pressure.
 3. An automatic liquid chemical mixer for use with a photographic film processor comprising: at least two chemical containers, each storing a different chemical, each of said containers including an outer structure defining a rigid volumetric container and a collapsible inner structure providing a liquid-tight seal; a reservoir having a small capacity in relation to said containers; and pumping means responsive to the level in said reservoir for transferring chemicals from said containers to the reservoir in selected proportions to maintain the quantity of fluid within the reservoir between specified limits.
 4. An automatic liquid chemical mixer for use with a photographic film processor comprising: at least two chemical containers, each storing a different chemical; a reservoir having a small capacity in relation to said containers; pumping means responsive to the level in said reservoir for transferring chemicals from said containers to the reservoir in selected proportions to maintain the quantity of fluid within the reservoir Between specified limits; and means for detecting an empty condition in one of said containers and providing a signal in response to such an empty condition, said signal activating a means for warning a machine operator and means for inhibiting said pumping means.
 5. An automatic liquid chemical mixer for use with a photographic film processor comprising: a storage container for Type A chemical solution; a storage container for Type B chemical solution; a storage container for working solution; means connecting the chemical mixer to a water supply; a reservoir having a small capacity in relation to said containers for Type A and Type B chemical solution; pumping means responsive to the level in said reservoir for transferring chemicals from said containers for Type A and Type B chemical solution to the reservoir in selected proportions to maintain the quantity of liquid within the reservoir between specified limits; means for transferring fluid from the reservoir to the film processor upon demand; means for transferring fluid from said storage container for working solution to the film processor upon demand; and means for providing water to the film processor upon demand.
 6. For use with an automatic film processor, a chemical supply device comprising: a chemical supply system providing a Type A and Type B chemical mixer for given demand rates from a demand system, demand being independently intermittent or continuous comprising: a pair of collapsible containers for Type A and Type B chemicals respectively; a pair of pumps, each coupled to a different container, and each having a rate proportionately higher than a given demand rate; a closed reservoir coupled to the pair of pumps and including means coupling to the demand system, said reservoir drawing a substantially smaller capacity than said containers; and liquid level sensing means coupled to said reservoir and controlling said pair of pumps.
 7. The chemical supply device of claim 6 further including solenoid valve means connected between the pumps and the reservoir and time delay means responsive to the level sensing means controlling the valve means. 